The incidence of gonorrhea has decreased during the last decade. In stark contrast to this downward trend, the proportion of strains showing drug resistance has increased. Penicillin resistant strains were first reported in 1976 and, since that time, drug resistant Neisseria gonorrhoeae isolates from various parts of the world have been described. Although some quinolones and extended-spectrum cephalosporins are currently proving adequate for a treatment regimen, species vulnerability will likely diminish and antimicrobial resistance is a matter of time. Physiological adaptability and evasion of immune host response contribute to microbial persistence and many of these strategies can be manifested through and by the components of the outer surface Hpooligosaccharide (LOS). Foremost, and probably related, are the demonstrable antigenic variations and oligosaccharide (OS) heterogeneity. Transparent to a significant part of these differences is the mAb 2C7, which recognizes an OS epitope that is widely expressed in vivo. A better understanding of the structural features of reactivity for 2C7 may provide an improved basis for gonococcal vaccine development. In this investigation, using several known andone unknown LOS, we are carrying out their structural characterization using simple chemical manipulations and the mass spectrometry techniques of electrospray ionization, collision-induced decomposition tandem mass spectrometry.